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\multicolumn{2}{|c|}{\LARGE\bf THE\hspace*{1cm}STAR\hspace*{1cm}FORMATION\hspace*{1cm}NEWSLETTER} \\ [0.3cm]
\multicolumn{2}{|c|}{\large\em An electronic publication dedicated to early stellar evolution and molecular clouds} \\ [0.3cm]
{\hspace*{0.8cm} No. 2 --- 1 Nov 1992 } & \multicolumn{1}{r|}{Editor: Bo Reipurth (reipurth@eso.org)\hspace*{0.8cm}} \\ [-0.1cm]
& \\ \hline
\end{tabular}
\vspace*{1cm}
\begin{center}
{\Large\em From the Editor}
\end{center}
\vspace*{0.6cm}
I am happy to report that the first issue of the Star Formation Newsletter
was met with great enthusiasm. About 200 persons replied to
the first mailing, so a large fraction of the community is now
receiving the Newsletter, and the mailing list continues to grow every day. \
It thus appears that our principal goal, i.e. to provide the community with
rapid dissemination of the latest research results in a comprehensive manner,
can be met. \ If you have received this issue you are on the mailing list
until you notify me to the contrary.
\ Those who have not responded to the first mailing are no
longer on the mailing list, as I do not want to fill peoples mailboxes
with unsolicited mail.
I plan within a year from now to circulate a questionnaire
with suggestions for improvements, but first the newsletter has to get
into a more quiet phase, where it is
more of a routine affair to produce than it is now. One activity that
we are looking into is the possibility of creating a preprint data
base, where people can pick up preprints, thus bypassing the
cumbersome mailing of preprints upon every request. But this is not a
trivial thing to develop, and it will take its time.
In this issue, we introduce a new section, Job Offers, in which jobs focused
towards stellar and planetary formation, associated phenomena and molecular clouds
are advertised. \ The two jobs listed this month come from the AAS Job Register,
but institutes that are particularly looking for applicants, whether junior or
senior, with interests in the above fields are invited to send their advertisements
for inclusion in the Newsletter.
\vspace*{1cm}
\begin{center}
{\Large\em Abstracts of recently accepted papers}
\end{center}
\vspace*{0.6cm}
%% Between these brackets you write the title of your paper:
{\large\bf{Bipolar structure of the Herbig-Haro object RNO40}}
%% Here comes the author(s) of the paper, please indicate within $^...$
%% the number which corresponds to the institute of each author.
{\bf{ J. Bohigas$^1$, P. Persi$^2$ and M. Tapia$^1$ }}
%% Here you write your institute name(s) and address(es),
%% the number in $^..$ indicates your author number, for example:
$^1$ {Instituto de Astronomia, UNAM, Apdo. Postal 877, Ensenada, BC, Mexico} \\
$^2$ {Istituto Astrofisica Spaziale, CNR, c.p. 67, I-00044, Italy}
%% Within the following brackets you place your text:
{Images of the Herbig--Haro object RNO 40 and its vicinity
are presented covering the wavelength range $\lambda \lambda
600 - 2400$ nanometers. These include narrow band images in the
lines H$\alpha$, [NII], [SII] and [OI]. A bipolar morphology
centred in RNO 40 is found. Both lobes are defined by a series of
fainter HH knots to the SE and NW of the brightest central peak. An
elongated bar--like emission is seen on the SE lobe. The infrared
images show the central nebular peak and a series of knots not
always coincident with those found in the optical images. Although
no star was detected in the nearby 23'', the morphology
of the complex argues in favour of the location of the
exciting source close to the central emission peak and against the
identification of the far infrared source IRAS05173--0555, located
2' away, as the source of excitation.}
% Here you write which journal accepted your paper, for example:
{ Accepted by Astron. Astrophys.}
\vspace*{0.5cm}
\newpage
{\large\bf{Protostellar Hydrodynamics: Constructing and Testing a
Spatially and Temporally Second-Order Accurate Method.
I. Spherical Coordinates}}
{\bf{Alan P. Boss$^1$ and Elizabeth A. Myhill$^{1-2}$}}
$^1$ {DTM, Carnegie Institution of Washington, 5241 Broad Branch Road, NW,
Washington, DC 20015, USA} \\
$^2$ {Department of Earth and Space Sciences,
University of California, Los Angeles, CA 90024-1567, USA}
{ An explicit, Eulerian numerical
method for computing the collapse of protostellar
clouds has been developed. The method has been applied to a family of
codes of increasing dimensionality: spherically symmetric (1D), axisymmetric
(2D), and fully three dimensional (3D).
The method employs spatially second-order accurate
advective fluxes based on van Leer monotonic interpolation and consistent
advection,
generalized to a spherical coordinate grid. Correction terms for the
effects of spherical geometry on the advective terms are included in order
to achieve a high degree of accuracy on the pressureless collapse test case.
Self-gravity is handled by a spherical harmonic expansion of the
Poisson equation, and radiative transfer through the solution
of a mean intensity equation in the Eddington approximation.
Correction terms necessary to make the code temporally second-order accurate
have also been derived and implemented in the code, though for
most test cases the temporal corrections have little or no discernible
effect when compared to results obtained with the temporally first-order
accurate version of the codes.
The numerical methods have been shown to be second-order accurate through
convergence testing.
Global conservation of mass, angular momentum,
and internal energy are assured by solving the hydrodynamical equations
in conservation law form.
The method for transport of angular momentum has been
chosen to optimize local conservation of angular momentum, as monitored
by the preservation of the specific angular momentum spectrum during
axisymmetric collapse.
The results of a number of other test cases are presented as well.
The reduction of systematic errors in the new code
should result in general in the prediction of an
enhanced role for fragmentation during protostellar collapse.}
{ Accepted by Astrophys. J. Suppl.}
\vspace*{0.5cm}
%% Between these brackets you write the title of your paper:
{\large\bf{The H$_{2}$ Velocity Field in Herbig-Haro 7 to 11}}
%% Here comes the author(s) of the paper, please indicate within $^...$
%% the number which corresponds to the institute of each author.
{\bf{ John S. Carr$^1$ }}
%% Here you write your institute name(s) and address(es),
%% the number in $^..$ indicates your author number, for example:
$^1$ { Department of Astronomy, The Ohio State University,
174 W. 18th Ave., Columbus, OH 43210 }
%% Within the following brackets you place your text:
{Fabry-Perot images of the H$_{2}$ 1-0 S(1) emission line in Herbig-Haro 7
to 11 have been obtained with a velocity resolution of 25 km s$^{-1}$ and
a spatial resolution of 1.2 arcsec. The H$_{2}$ line profiles peak at lower
(absolute) radial velocity than the atomic lines and have smaller line
widths (FWHM). However, the H$_{2}$ profiles have weak high-velocity
wings, and the full width at zero intensity velocities are similar to
those of the atomic lines. In the vicinity of HH 11, the velocity extent
of the H$_{2}$ emission is greater than 200 km s$^{-1}$. It is suggested
that the weak emission near HH 11 may be produced by H$_{2}$ reformation
pumping in fast shocks and that the extremely high-velocity CO
observed in the same region could have a similar origin. The H$_{2}$
emission in HH 7 has the velocity field expected for a radiating bow-
shock, with strong H$_{2}$ emission at the apex of the bow-shock. It is
suggested that the H$_{2}$ emission from HH 7 consists of two
components: (1) a magnetic precursor in a high-velocity (~ 100 km s$^{-1}$)
J-shock which produces most of the H$_{2}$ emission, and (2) a post-
shock component that is responsible for the weak high-velocity
emission. The post-shock component could be reformation pumping
or emission from H$_{2}$ that has survived dissociation in the shock front.
A theoretical bow-shock with a simple parameterized model for the
magnetic precursor is presented to explain the observed velocity
field in HH 7. J-shocks with magnetic precursors are the most
attractive explanation for the combined optical and infrared data,
although detailed theoretical calculations of such shocks are required.}
% Here you write which journal accepted your paper, for example:
{ Accepted by Astrophys. J. }
\vspace*{0.5cm}
%% Between these brackets you write the title of your paper:
{\large\bf{IR and Optical Imaging of IRAS Sources with CO Outflow:
A Snapshot of Early Star Formation}}
%% Here comes the author(s) of the paper, please indicate within $^...$
%% the number which corresponds to the institute of each author.
{\bf{ H. Chen$^1$, A.T. Tokunaga$^1$, K.M. Strom$^2$ \ and K.-W. Hodapp$^1$ }}
%% Here you write your institute name(s) and address(es),
%% the number in $^..$ indicates your author number, for example:
$^1$ {Inst. for Astronomy, U. of Hawaii, 2680 Woodlawn Dr. Honolulu, HI 96822} \\
$^2$ {Five College Astronomy Department, U. of Mass., Amherst, MA 01003}
%% Within the following brackets you place your text:
{
We present multiband imaging (BVRI and HK'nbLM) of three IRAS sources
(05338-0624, 05339-0626, and 05363-0702) associated with CO molecular
outflows. We find stellar density enhancements around all three IRAS
sources. Optical and near-IR photometry indicates that at least 60\%
of the near-IR sources in the vicinity of the IRAS sources are pre-main-
sequence stars. Using the photometric data at nbL and M, we are able
to identify candidates for the near-IR counterparts of the IRAS sources.
We also find that (1) the spectral energy distribution of the deeply
embedded sources could be complicated by source confusion and scattered
light from the young stellar objects; (2) star formation in the vicinity
of the IRAS sources is a continuous process with an age span of 0.5-3 Myr;
and (3) stellar density enhancement is probably a phenomenon found at
the earliest stage of star formation.
}
% Here you write which journal accepted your paper, for example:
{ Accepted by Astrophys. J. }
\vspace*{0.5cm}
%% Between these brackets you write the title of your paper:
{\large\bf{The Radio Continuum Morphology of the Orion Nebula:
from 10$'$ to 0.1$''$ Resolution}}
%% Here comes the author(s) of the paper, please indicate within $^...$
%% the number which corresponds to the institute of each author.
{\bf{ Marcello Felli$^1$, Ed Churchwell$^2$, Tom L. Wilson$^3$ \ and
Gregory B. Taylor$^4$ }}
%% Here you write your institute name(s) and address(es),
%% the number in $^..$ indicates your author number, for example:
$^1$ {Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze,
Italy} \\
$^2$ {University of Wisconsin, 475 N. Charter St., Madison, WI 53706, U.S.A.} \\
$^3$ {Max-Planck-Institut f\"ur Radioastronomie, Auf dem Hugel 69,
D-5300 Bonn 1, Germany} \\
$^4$ {Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze
Italy, now at California Institute of Technology, Radio Astronomy,
105-24, Pasadena, CA 91125, U.S.A.}
%% Within the following brackets you place your text:
{A complete set of newly measured radio continuum maps of the Orion Nebula at 20
and 2 cm is presented. The largest field covers a region of 2$^\circ$ $\times$
2$^\circ$ with a resolution of 10$'$, the smallest covers a 3$'$
$\times$ 3$'$ field, centered on the peak, with a resolution of 0.1$''$.
The lower resolution maps emphasize the extended emission of the diffuse
ionized gas. As the resolution increases, the maps sample regions of higher
emission measure. A detailed comparison with H$\alpha$ images shows a very
good match on all scale sizes. As the resolution becomes finer than 1$''$ a
completely new aspect of the radio emission appears: a new class of weak, small
diameter sources of high surface brightness are found. Many of these features
are associated with stars.
Finally,
a morphological comparison of the radio continuum emission
with similar-scale maps of molecular and atomic emission is presented. }
% Here you write which journal accepted your paper, for example:
{ Accepted by Astron. and Astrophys. Suppl. }
\vspace*{0.5cm}
%% Between these brackets you write the title of your paper:
{\large\bf{The molecular outflow very near L1551 IRS5}}
%% Here comes the author(s) of the paper, please indicate within $^...$
%% the number which corresponds to the institute of each author.
{\bf{ C.V.M. Fridlund$^1$, L.B.G. Knee$^2$ }}
%% Here you write your institute name(s) and address(es),
%% the number in $^..$ indicates your author number, for example:
$^1$ {Astrophysics Division, Space Science Department, ESTEC, Postbox
299, NL-2200AG, Noordwijk, The Netherlands} \\
$^2$ {Onsala Space Observatory, S-439 00 Onsala, Sweden}
%% Within the following brackets you place your text:
{
Observations of the molecular transitions CO
(J=1-0), $^{13}$CO (J=1-0) and HCO$^+$(J=1-0)
towards the driving source of the bipolar
molecular outflow in L1551, are presented. They show that outflowing
gas is present within 2500 AU of the driving source, L1551 IRS5, and
that molecular gas dense enough to excite HCO$^+$ is
present. The mass loss rate close to IRS5 is found to be within an
order of magnitude of the value determined earlier from global properties
of the outflow. This implies that the average mass loss rate has not
changed significantly during the dynamical life time of the outflow.}
% Here you write which journal accepted your paper, for example:
{ Accepted by Astron. Astrophys. }
\vspace*{0.5cm}
%% Between these brackets you write the title of your paper:
{\large\bf{Ammonia Clumps in the Orion and Cepheus Clouds}}
%% Here comes the author(s) of the paper, please indicate within $^...$
%% the number which corresponds to the institute of each author.
{\bf{ J.Harju$^1$, C.M.Walmsley$^2$
\ and J.G.A.Wouterloot$^3$ }}
%% Here you write your institute name(s) and address(es),
%% the number in $^..$ indicates your author number, for example:
$^1$ {Observatory and Astrophysics Laboratory, University of
Helsinki, T\"{a}htitorninm\"{a}ki, SF-00130 Helsinki, Finland } \\
$^2$ {Max Planck Institut f\"{u}r Radioastronomie, Auf dem H\"{u}gel
69, D-5300 Bonn 1, Germany} \\
$^3$ {I Physikalisches Institut, University of Cologne,
Z\"{u}lpicherstrasse 77, D-5000 K\"{o}ln 41, Germany}
%% Within the following brackets you place your text:
{We present integrated intensity maps made with the Effelsberg 100-m
telescope of the (1,1) and (2,2) transitions of ammonia towards
43 star formation regions in nearby molecular clouds. Of these
regions, 16 are associated with the Orion L1630 and L1641 clouds
and 21 with the molecular complexes in Cepheus. As well as the
ammonia cores apparently associated with embedded IRAS sources, we have
found and mapped 12 nearby clumps which have no known associated
infrared objects. For these cores, we derive sizes, masses, mean
temperatures, and velocity dispersions. We compare the characteristics
of the cores in our samples with earlier studies of clumps in Taurus by
Benson and Myers (1983,1989). The clumps in Orion and Cepheus are found
to be larger, warmer, more massive, and to have greater velocity
dispersions than the Taurus cores. If one uses the linear separation
between IRAS sources and their associated ammonia cores as a measure of
age, one finds that the infrared sources in Orion are young relative
to those found in the other complexes.}
% Here you write which journal accepted your paper, for example:
{ Accepted by Astron.Astrophys. Supplements }
\vspace*{0.5cm}
%% Between these brackets you write the title of your paper:
{\large\bf{A Flattened Cloud Core in NGC~2024}}
%% Here comes the author(s) of the paper, please indicate within $^...$
%% the number which corresponds to the institute of each author.
{\bf{ Paul T.~P.~Ho$^1$, Yun-Lou~Peng$^2$,
Jos\'{e} M.~Torrelles$^{3,1}$,
Jos\'{e} F. G\'omez$^{1,3}$,
Luis F. Rodr\'\i guez$^4$, and Jorge Cant\'o$^4$}}
%% Here you write your institute name(s) and address(es),
%% the number in $^..$ indicates your author number, for example:
$^1$ Harvard-Smithsonian Center for Astrophysics,
60 Garden Street, Cambridge, MA 02138.\\
$^2$ Nanjing University, Nanjing, PRC.\\
$^3$ Instituto de Astrof\'{\i}sica de Andaluc\'{\i}a, CSIC,
Ap. Correos 3004,
C/ Sancho Panza S/N, E-18080 Granada, Spain.\\
$^4$ Instituto de Astronom\'{\i}a, UNAM, Ap. Postal 70-264,
04510 M\'{e}xico, D.F., M\'{e}xico.
%% Within the following brackets you place your text:
The (J,K) = (1,1) and (2,2) NH$_3$ lines were mapped toward a molecular cloud
core in NGC~2024 using the VLA in its C/D configuration. This region is
associated with one of the most highly collimated molecular outflows. We find
that the molecular condensations associated with FIR~5, 6, and 7 have kinetic
temperatures T$_{\rm K}$ $\simeq$ 40~K. We also find line broadening toward
FIR~6 and FIR~7. This suggests that these condensations may not be protostars
heated by gravitational energy released during collapse, but that they have an
internal heating source. A flattened structure of ammonia emission is found
extending parallel to the unipolar CO outflow structure, but displaced
systematically to the east. If the NH$_3$ emission traces the denser gas
environment, there is no evidence that a dense gas structure is confining the
molecular outflow. Instead, the location of the high velocity outflow along
the surface of the NH$_3$ structure suggests that a wind is sweeping material
from the surface of this elongated cloud core.
% Here you write which journal accepted your paper, for example:
{ Accepted by Astrophys.J }
\vspace*{0.5cm}
%% Between these brackets you write the title of your paper:
{\large\bf{The Distance to the Lupus
Star Formation Region}}
%% Here comes the author(s) of the paper, please indicate within $^...$
%% the number which corresponds to the institute of each author.
{\bf{ Joanne Hughes$^1$, Patrick Hartigan$^1$ \ and Lori Clampitt$^2$ }}
%% Here you write your institute name(s) and address(es),
%% the number in $^..$ indicates your author number, for example:
$^1$ {Five College Astronomy Department, University of Massachusetts, Amherst MA 01003} \\
$^2$ {Five College Astronomy Department, Smith College, Northampton MA 01063}
%% Within the following brackets you place your text:
{We use photometric and spectroscopic observations of 31 field stars
in Lupus to determine the distance to the dark clouds. A plot of
extinction vs\hbox{.} distance for the field stars indicates a distance of $140\pm 20$~pc
to the Lupus clouds, which is at the lower end of the range defined by previous estimates.
One of the ``field'' stars has weak H$\alpha$ emission and a far-infrared excess,
indicating that it is a previously uncatalogued pre-main sequence star.}
% Here you write which journal accepted your paper, for example:
{ Accepted by Astron. J. }
\vspace*{0.5cm}
%% Between these brackets you write the title of your paper:
{\large\bf{Interacting H$_2$O Masers in Star-forming Regions}}
%% Here comes the author(s) of the paper, please indicate within $^...$
%% the number which corresponds to the institute of each author.
{\bf{ Nikolaos D. Kylafis \ and Konstantinos G. Pavlakis}}
%% Here you write your institute name(s) and address(es),
%% the number in $^..$ indicates your author number, for example:
{Univ. of Crete, Physics Dept., 714 09 Heraklion, Crete, Greece}
%% Within the following brackets you place your text:
{
We have studied the interaction of H$_2$O masers in star forming regions
(and through it the enhancement of the observed luminosity) as a physical
mechanism for the explanation of the very strong H$_2$O maser sourses.
For each individual maser we have taken a collisional pump model. Such a
model can explain the low and medium luminosity masers but not the very
powerful ones. We have carried out detailed numerical calculations for
both saturated and unsaturated masers and have derived approximate
analytic expressions for the expected brightness temperature from
interacting masers. We have found that the interaction of two low or
medium power H$_2$O masers can in principle lead to the appearance of a
very strong one. Extremely strong OH masers have not been observed
yet, but this could be a result of interstellar scattering.
}
% Here you write which journal accepted your paper, for example:
{ Accepted by Astrophys. J. }
\vspace*{0.5cm}
%% Between these brackets you write the title of your paper:
{\large\bf{New Herbig-Haro objects and pre-main sequence stars in the
star formation region NGC 7129}}
%% Here comes the author(s) of the paper, please indicate within $^...$
%% the number which corresponds to the institute of each author.
{\bf{ L. F. Miranda$^1$, C. Eiroa$^2$ \ and A. I. Gomez de Castro$^3$ }}
%% Here you write your institute name(s) and address(es),
%% the number in $^..$ indicates your author number, for example:
$^1$ {Dpto. de Astrofisica, Facultad de Ciencias Fisicas, Universidad
Complutense de Madrid, 28040 Madrid, Spain} \\
$^2$ {Dpto. Fisica Teorica C-XI, Facultad de Ciencias, Universidad Autonoma
de Madrid, Cantoblanco, 28049 Madrid, Spain} \\
$^3$ {ESA-IUE Observatory, Villafranca Satellite Tracking Station, P.O. Box
50727, 28080 Madrid, Spain}
%% Within the following brackets you place your text:
{We present CCD images of the central part of the star forming region NGC 7129
as well as spectra of moderate spectral and high spatial resolution of some
nebular objects and stars. The images show many reflection filaments which seem
to trace the edges of the molecular cavity associated with the pre-main-
sequence star LkH$\alpha$ 234. Three new T Tauri-like stars and five new Herbig-Haro
(HH) objects have been identified in the region. One of the new young stars
probably illuminates an elongated reflection filament. One of the new HH objects
presents a highly collimated structure and an abrupt and unusually large bending
of $\approx$ 90$^{\circ}$ . The object emanates from the H$\alpha$ -emission
line star HL 14. Our spectra indicate that this star is likely to be a T Tauri-
like star. Large and systematic variations of the radial velocity, electron
density, excitation degree and velocity dispersion exist in the object. The
data favor the idea that the object is a jet-like outflow which encounters an
obstacle -density enhancement or pressure gradient- in the cloud and deflects.
The obstacle could be related to the walls of the molecular cavity associated
with LkH$\alpha$ 234 or to the energetic wind from this star}
% Here you write which journal accepted your paper, for example:
{ Accepted by Astronomy and Astrophysics }
\vspace*{0.5cm}
%% Between these brackets you write the title of your paper:
{\large\bf{ Formation of Double-peaked Lines in Stochastic Winds of
T Tauri Stars}}
%% Here comes the author(s) of the paper, please indicate within $^...$
%% the number which corresponds to the institute of each author.
{\bf{ A.S.Mitskevich$^1$, A.Natta$^1$ \ and V.P.Grinin$^2$ }}
%% Here you write your institute name(s) and address(es),
%% the number in $^..$ indicates your author number, for example:
$^1$ {Osservatorio di Arcetri, Largo Fermi 5, 50125 Firenze, Italy} \\
$^2$ {Crimean Astrophysical Observatory, p/o Nauchny, 334413, Ukraina}
%% Within the following brackets you place your text:
{ This paper discusses the formation of spectral lines in stochastic
moving media. The method used to solve the radiation transfer is based on that
developed by Lindsey $\&$ Jefferies 1990 for static, inhomogeneous media.
Both the wind structure (i.e., the
velocity, size and filling factor of the clumps which form
the wind) and the gas radiative properties
(i.e., optical depth and source function at each distance from the star)
are considered as free parameters.
Most of the calculations are intended to investigate the formation of
of double-peaked line profiles, as those
often seen in H$\alpha$ in T Tauri stars,
and their dependence on the wind parameters.
Within the limits set by the adopted parametric description of the
wind properties, we find that
the observed features can be understood if the winds
are clumpy and decelerate at large distance from the star.
By comparing the model calculations to several observed H$\alpha$ spectra,
we assign a typical clump size near the stellar surface of $\leq$0.1
stellar radii,
and a volume filling factor of about 0.1.
>From the depth of the absorption dip,
there is an indication that the wind remains clumpy also at large
distances from the star.
Some results for lines of intermediate optical depth are also
discussed.
We find that in this case the profiles are similar to those
obtained in
continuous winds of much lower optical depth.
In stochastic winds, it is therefore possible to have lines, which, while
forming in an optically thick gas,
have profiles typical of optically thin conditions.
This fact can explain
the properties of the Ca II infrared triplet lines in many T Tauri stars.}
% Here you write which journal accepted your paper, for example:
{ Accepted by Astrophys. J. }
\vspace*{0.5cm}
%% Between these brackets you write the title of your paper:
{\large\bf{Sensitive imaging polarimetry of the faint IR reflection
nebula in B5\,IRS1}}
%% Here comes the author(s) of the paper, please indicate within $^...$
%% the number which corresponds to the institute of each author.
{\bf{ T.J.T. Moore$^1$ \& J.P. Emerson$^2$ }}
%% Here you write your institute name(s) and address(es),
%% the number in $^..$ indicates your author number, for example:
$^1$ {Herzberg Institute for Astrophysics, National Research Council,
Ottawa, Ontario K1A 0R6, Canada} \\
$^2$ {Physics Department, Queen Mary \& Westfield College, Mile End
Road, London E1 4NS, UK}
%% Within the following brackets you place your text:
{Sensitive J, H, K imaging polarimetry of the low-mass young stellar
object B5 IRS1 reveals a very faint reflection nebula (mean K surface
brightness $\simeq 7 \mu$Jy arcsec$^{-2}$), composed of light scattered
in a thin, limb-brightened dust shell associated with the blue-shifted
lobe of the weak molecular outflow from IRS1 itself. It appears that
the flow is collimated on scales of $\sim$20 arcseconds by partial
pressure confinement within the shell and that the shell density is
maintained by residual lateral expansion of the flow. The polarization
pattern close to the source suggests a disk around IRS1 and anomalous
polarization patterns in the nebula are found to be qualitatively
consistent with scattering from a population of grains deficient in
sizes smaller than $\sim$0.5\,$\mu$m.
As in other reflection nebulae, the surface brightness gradient in the
scattered light is much shallower than $\theta^{-2}$. An explanation
for this is sought by postulating gradients in extinction, scattering
optical depth or grain albedo across the nebula. Forward-biased scattering
alone can produce a shallow brightness distribution but, if isotropic
scattering is assumed, an extinction gradient similar to that predicted for a
collapsing protostellar core provides the best model of the current data.
Multi-epoch photometry at J, H and K, compared with
existing data, shows that the near-infrared luminosity of the source
has declined significantly between 1983 and 1990 without significant
change in colour. We suggest that this may indicate the growth of large
grains (with colour-neutral extinction) in the disk around IRS1 and speculate
that this process may lead to the formation of planetesimals.}
% Here you write which journal accepted your paper, for example:
{ Accepted by M.N.R.A.S.}
\vspace*{0.5cm}
%% Between these brackets you write the title of your paper:
{\large\bf{Imaging polarimetry of the bipolar nebula Parsamyan 22}}
%% Here comes the author(s) of the paper, please indicate within $^...$
%% the number which corresponds to the institute of each author.
{\bf{ S.M. Scarrott$^1$, P.W.Draper$^1$ \ and C.N.Tadhunter$^2$ }}
%% Here you write your institute name(s) and address(es),
%% the number in $^..$ indicates your author number, for example:
$^1$ {Physics Department, University of Durham, South Road, Durham, DH1 3LE} \\
$^2$ {Physics Department, University of Sheffield, Sheffield S37RH.}
%% Within the following brackets you place your text:
{Par 22 shows high levels of polarization which confirm that it is a bipolar reflection
nebula. We suggest that circumstellar material which is very patchy and forms
fingers which penetrate the central regions of the nebula is the remnant of the
circumstellar disc which is in the process of disintegration. We take this as an
indication that the system is in the later stages of pre-main-sequence evolution.
We discuss the origin of the sharp rim/diffuse boundary of each of the nebular
lobes.}
% Here you write which journal accepted your paper, for example:
{ Accepted by MNRAS }
\vspace*{0.5cm}
%% Between these brackets you write the title of your paper:
{\large\bf{Circularly Polarized Radio Emission from the T Tauri
Star Hubble 4}}
%% Here comes the author(s) of the paper, please indicate within $^...$
%% the number which corresponds to the institute of each author.
{\bf{ Stephen L. Skinner$^1$ }}
%% Here you write your institute name(s) and address(es),
%% the number in $^..$ indicates your author number, for example:
$^1$ {JILA, Campus Box 440, Univ. of Colorado, Boulder, CO 80309-0440 USA}
%% Within the following brackets you place your text:
{I discuss multiwavelength VLA observations of the weak-lined T Tauri
star (WTTS) Hubble 4 (Herbig \& Bell no. 374), located in Taurus-Auriga.
A near-simultaneous detection at 3.6, 6, and 20 cm yielded a
flat spectral energy distribution with a spectral index $\alpha \approx$ 0.
The star was in a state of low radio activity (``quiescence") with
flux densities in the range 1.3 - 1.7 mJy. The emission at {\em both}
3.6 and 6 cm is right circularly polarized at levels of 19 ($\pm$5)\%
and 18 ($\pm$3)\% respectively, with an upper limit of $\leq$15\%
(3$\sigma$) at 20 cm. This provides direct evidence for the existence
of ordered magnetic fields in Hubble 4. An interpretation of the emission
in terms of optically thin gyrosynchrotron radiation implies magnetic
field strengths of a few tens of Gauss in the radio-emitting region.
The field strength at the stellar surface is not known, but values as
large as a few kilo-Gauss are not ruled out.
Observations taken $\approx$
7 months apart showed no change in the helicity or degree of polarization,
and suggest that the magnetic field structure may remain stable for
relatively long periods. These new data sharpen the radio analogy between
WTTS and RS CVn binaries, and provide further encouragement
that the magnetosphere
models now under development for RS CVns may also apply qualitatively to
WTTS}.
% Here you write which journal accepted your paper, for example:
{ Accepted by Astrophys. J. }
\vspace*{0.5cm}
%% Between these brackets you write the title of your paper:
{\large\bf{High resolution CO observations of S88-B}}
%% Here comes the author(s) of the paper, please indicate within $^...$
%% the number which corresponds to the institute of each author.
{\bf{ G.J. White$^1$, C.V.M. Fridlund$^2$ }}
%% Here you write your institute name(s) and address(es),
%% the number in $^..$ indicates your author number, for example:
$^1$ {Department of Physics, Queen Mary and Westfield College,
University of London, Mile End Road, London E1 4NS, England} \\
$^2$ {Astrophysics Division, Space Science Department, ESTEC, Postbox
299, NL-2200AG, Noordwijk, The Netherlands}
%% Within the following brackets you place your text:
{CO J=2-1 and $^{13}$CO J = 2-1 and 1-0
observations have been made of the HII region S88-B
using the 15m James Clerk Maxwell telescope in Hawaii,
and the 20m telescope at Onsala. The
core of the cloud is resolved into a horseshoe-like structure which
surrounds a diffuse reflection
nebula. The central core has a mass of $\geq$ 1000 solar masses,
with 400 solar masses in the horseshoe structure. The gas in
the horseshoe appears highly
fragmented, and has a kinetic temperature of $\approx$ 60 K,
suggesting it is closely coupled to the dust temperature.
A recently formed high mass star appears to be in
the process of evacuating a cavity, possibly through a
large molecular outflow that is found to show an accelerated
component in its blue-shifted lobe. A velocity gradient across the
horseshoe structure suggest ordered motion, and could represent
rotation in the parental cloud.}
% Here you write which journal accepted your paper, for example:
{ Accepted by Astron. Astrophys. }
\vspace*{0.5cm}
%% Between these brackets you write the title of your paper:
{\large\bf{Emission-line stars in L1641}}
%% Here comes the author(s) of the paper, please indicate within $^...$
%% the number which corresponds to the institute of each author.
{\bf{ J.G.A. Wouterloot$^1$ and J. Brand$^{2,*}$ }}
%% Here you write your institute name(s) and address(es),
$^1$ {I. Physikalisches Institut, Z\"ulpicher Stra\ss e 77, D-W-5000
K\"oln 41, FRG} \\
$^2$ {Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5,
50125 Firenze, Italy} \\
$^*$ {Present address: Istituto di Radioastronomia, CNR, Via Irnerio 46,
40126 Bologna, Italy}
%% Within the following brackets you place your text:
{We have searched for H$\alpha$ emission-line stars in a one square degree area
in the molecular cloud L1641 located in the Orion-South complex, and detected
112 stars with
H$\alpha$ strength between 1 (weak) and 4 (strong). In 87 of these stars,
H$\alpha$ emission has been detected for the first time. In L1647 we found three
candidate emission-line stars. Subsequently, we obtained
spectra of 27 of the stars in L1641 in the wavelength interval
5000-6700 \AA\ and derived spectral types and emission-line
strengths. We compare the distribution and properties of emission-line stars in
Orion with those in the Taurus dark clouds. Although a definite comparison is
still hampered by selection effects, it seems clear that Orion is more
efficient in low-mass star formation as well as massive star formation.}
% Here you write which journal accepted your paper, for example:
{ Accepted by Astronomy \& Astrophysics }
\vspace*{0.5cm}
%% Between these brackets you write the title of your paper:
{\large\bf{IRAS sources beyond the solar circle.
III. Observations of H$_{2}$O, OH, CH$_{3}$OH and CO.}}
%% Here comes the author(s) of the paper, please indicate within $^...$
%% the number which corresponds to the institute of each author.
{\bf{ J.G.A. Wouterloot$^1$, J. Brand$^{2,*}$ and K. Fiegle$^1$}}
%% Here you write your institute name(s) and address(es),
%% the number in $^..$ indicates your author number, for example:
$^1$ {I. Physikalisches Institut der Universit\"at zu K\"oln,
Z\"ulpicher Stra\ss e 77, D-W-5000 K\"oln 41, Germany} \\
$^2$ {Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5,
I-50125 Firenze, Italy} \\
$^*$ {Present address: Istituto di Radioastronomia, CNR, Via Irnerio 46,
I-40126 Bologna, Italy}
%% Within the following brackets you place your text:
{We have used the 100-m Effelsberg and 32-m Medicina radiotelescopes to search
for H$_{2}$O maser emission (22.235~GHz) towards 1143 IRAS sources, for OH
(1665/67 MHz) towards 303 IRAS sources, and for CH$_{3}$OH (12.179~GHz)
towards 19 IRAS sources. The IRAS sources have been selected to have colours of
pre-main sequence objects. To obtain an estimate of the (kinematic) distance we
observed $^{12}$CO(J=2$\to$1) and $^{12}$CO(J=3$\to$2) with the KOSMA 3-m
telescope towards 25 sources showing H$_{2}$O emission and not yet observed in
CO. This paper presents the observational results in form of tables with line
parameters or upper limits and spectra of detected sources. The analysis of
these data will be published separately.}
% Here you write which journal accepted your paper, for example:
{ Accepted by Astronomy \& Astrophysics Supplements}
\vspace*{0.5cm}
\newpage
\begin{center}
{\Large\em New Jobs}
\end{center}
\vspace*{0.6cm}
{\large\bf Research Associate} \ {\bf (Stellar and Planetary System Formation)}
Carnegie Institution of Washington \\
Department of Terrestrial Magnetism \\
5241 Broad Branch Road, NW \\
Washington, DC 20015--1305, USA
{\em Attention: Origins Associateship}
Applications are invited for a NASA-supported postdoctoral research associateship
in the general area of stellar and planetary system formation. \ The associate
will work with Alan Boss on theoretical models of the interactions of interstellar
shock waves with dense cloud cores and on cosmochemical implications (e.g.,
for meteorites) of the transport and mixing processes occurring during protostellar
collapse and disk evolution. \ The cosmogony group at DTM includes Alan Boss,
John Graham, and George Wetherill. \ DTM has a network of Sun SPARC stations,
an HP/Apollo 10040 workstation, a video production facility, and network access
to the national supercomputer centers.
The position requires a Ph.D. in a relevant field, experience with numerical
hydrodynamics codes, and excellent computer skills. \ The position will become
available July~1, 1993, and is available for one year, with the expectation
of a second year. \ The salary is \$32,000 per year, plus applicable benefits
and travel funds.
Applications should include a curriculum vita, a publication list, and three
letters of recommendation to be sent directly to us by those familiar with
your work. \ Completed applications are due by January 31, 1993.
Women and minority candidates are encouraged to apply.
\vspace*{0.5cm}
{\large\bf Staff Scientist Position} \ {\bf (Planet Formation, Origins of
Planetary Systems, ...)}
Lunar and Planetary Institute \\
3600 Bay Area Boulevard \\
Houston, TX 77058, USA
\vspace*{-0.3cm}
{\em \begin{tabbing}
Attention: \= Renu Malhotra \\
\> Chair, Search Committee
\end{tabbing} }
\vspace*{-0.3cm}
The Lunar and Planetary Institute is a center for research in planetary science
located in Houston, Texas, in close proximity to the Johnson Space Center. \ Areas
of current research at the Institute are diverse and include the study of lunar
and meteoritic materials, geophysical analysis of global datasets, and planetary
geology, including analysis of Voyager and other spacecraft data. \ Theoretical
studies include the origin of the solar system and other planetary systems and
solar system dynamics.
The Institute has two scientific staff positions available, starting in the
Fall of 1993, for a duration of two years with possibility of renewal. \
Scientists are expected to carry out original research in general areas of
planetary science. \ At the present time, we are particularly interested in
candidates conducting research in the areas of planet formation and origins
of planetary systems, planetary atmospheres, and science related to the planet
Mars. \ Applicants should send a curriculum vitae and a statement of research
interests and should arrange to have three letters of recommendation sent to
the above address.
\newpage
\begin{center}
{\Large\em Meetings}
\end{center}
\vspace*{0.6cm}
{\large\bf Circumstellar Matter 1994}
{\bf Dates:} \ 29 August -- 2 September 1994
{\bf Venue:} Heriot-Watt University Conference Centre, Edinburgh, Scotland
{\bf Intended Topics Include:}
\begin {itemize}
\item
star formation processes in molecular clouds
\item
formation and evolution of protostars
\item
circumstellar disk formation and subsequent evolution
\item
comparisons between low and high mass young stellar objects
\item
structure, dynamics and chemistry of Herbig-Haro objects and T Tauri stars
\item
dynamics, chemistry and evolution of outflows, winds and jets
\item
dynamics of evolved and post main sequence stars
\item
circumstellar dust, shell and envelope structure and chemistry
\item
mass loss from hot stars: Wolf-Rayet stars, OB and Ae/Be stars, FU
Orionis types, etc.
\item
instabilities and accelerations in flows and winds (ie: shocks, blobs,
winds, jets)
\item
features of Luminous Blue Variables
\item
role of magnetic field in star formation and early stellar evolution
\end {itemize}
{\bf Scientific Organizing Committee:}
J.E.Dyson, I.D.Howarth, H.Olofsson, G.Sandell, L.B.Waters
{\bf For further details contact:}
Graeme Watt (ROE)
Internet: gdw@starlink.roe.ac.uk
\end{document}